His displacement is actually the hypotenuse (c) of the triangle with sides 6 blocks and 8 blocks. According to the Pythagorean theoreme: c² = a² + b² c² = 6² + 8² c² = 36 + 64 c² = 100 c = √100 c = 10 blocks
Since 1 block is 500ft long, then 10 blocks are 5000 ft long: 1 : 500ft = 10 : x x = 10 * 500ft / 1 = 5000 ft